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Table 3 Sublingual and peripheral microvascular changes after a 2-hour exposure to hyperoxia and 2 h after return to baseline FiO2

From: Effects of short-term hyperoxia on erythropoietin levels and microcirculation in critically Ill patients: a prospective observational pilot study

 

t0

t1

t2

p (time)a

p (interaction)b

TVD small (mm/mm2)

    

-

  Hyperoxia

18.5 [16.5–21.6]**

16.4 [14.6–21.6]**

19.3 [18.2–21.3]‡*

0.035

 

  Controls

21.7 [20.0–23.8]

22.2 [18.8–24.3]

21.0 [19.8–23.7]

0.705

TVD medium (mm/mm2)

    

-

  Hyperoxia

0.9 [0.4–1.6]

0.5 [0.4–0.9]**

0.7 [0.3–1.3]

0.268

 

  Controls

1.2 [0.8–1.8]

1.0 [0.7–1.8]

1.1 [0.6–1.7]

0.861

PVD small (mm/mm2)

    

-

  Hyperoxia

17.4 [16.3–20.8]**

15.4 [13.2–20.3]**

18.4 [17.1–19.9]*

0.058

 

  Controls

20.1 [18.9–22.6]

21.0 [18.0–23.3]

20.0 [18.5–22.9]

0.549

PVD medium (mm/mm2)

    

0.178

  Hyperoxia

0.9 ± 0.6

0.6 ± 0.5*

0.8 ± 0.6

0.142

 

  Controls

1.2 ± 0.6

1.2 ± 0.6

1.1 ± 0.7

0.851

De Backer score (n/mm)

    

-

  Hyperoxia

11.2 [9.9–13.2]**

9.7 [8.8–13.2]**

11.8 [10.0–13.4]‡**

0.019

 

  Controls

14.5 [12.0–15.8]

14.1 [11.6–15.8]

14.1 [12.7–16]

0.951

MFI small (AU)

    

-

  Hyperoxia

2.74 [2.50–2.90]

2.67 [2.50–2.90]

2.75 [2.52–2.92]

0.713

 

  Controls

2.67 [2.44–2.90]

2.75 [2.60–3.00]

2.79 [2.67–2.98]

0.099

PPV small (%)

    

0.223

  Hyperoxia

96 ± 3

94 ± 4

95 ± 3

0.149

 

  Controls

94 ± 4

95 ± 3

95 ± 4

0.396

FHI small (AU)

    

-

  Hyperoxia

0.14 [0.08–0.21]

0.18 [0.09–0.30]*

0.10 [0.02–0.20]

0.551

 

  Controls

0.09 [0.02–0.19]

0.09 [0.00–0.18]

0.09 [0.00–0.18]

0.290

BFV (μm/s)

    

0.631

  Hyperoxia

497 ± 63

489 ± 81

502 ± 45

0.741

 

  Controls

520 ± 56

519 ± 54

531 ± 65

0.537

StO2 (%)

    

0.655

  Hyperoxia

80 ± 8

82 ± 8

82 ± 7

0.261

 

  Controls

81 ± 9

81 ± 8

82 ± 9

0.824

StO2 downslope (%/min)

    

-

  Hyperoxia

−7.9 [−9.1, −7.0]

−7.7 [−9.3, −6.8]

−9.4 [−11.0, −7.9]‡

0.003

 

  Controls

−8.1 [−9.7, −6.8]

−7.9 [−10.1, −7.0]

−8.6 [−9.9, −6.9]

0.212

StO2 upslope (%/min)

    

-

  Hyperoxia

133 [98–243]

194 [145–274]

192 [140–244]

0.101

 

  Controls

194 [150–228]

193 [139–262]

219 [132–263]

0.247

StO2 area under the curve (%*min)

    

0.284

  Hyperoxia

14.6 ± 8.8

18.0 ± 11.8

13.2 ± 7.6

0.066

 

  Controls

20.3 ± 15.1

19.8 ± 14.7

18.3 ± 13.3

0.660

THI (AU)

    

0.884

  Hyperoxia

11.0 ± 3.2

11.4 ± 3.8

11.8 ± 3.2

0.374

 

  Controls

12.6 ± 2.2

12.7 ± 3.5

13.0 ± 3.1

0.801

  1. Data are expressed as mean ± standard deviation or median [1st-3rd quartile], as appropriate. (t0): baseline; (t1): 2 h 1.0 FiO2; (t2): 2 h after the return to baseline FiO2. TVD total vessel density, PVD perfused vessel density, PPV proportion of perfused vessels, MFI microvascular flow index, FHI flow heterogeneity index, BFV blood flow velocity
  2. a Overall effect of time on the variance in each group. One-way ANOVA for repeated measures with Bonferroni’s post hoc test or Friedman test with Dunn’s test for multiple comparisons, as appropriate
  3. b Test of interaction between time and groups. Two-way ANOVA for repeated measures. This was applicable only to normally distributed variables
  4. *p < 0.05, **p < 0.01 versus controls (same time point); two-way ANOVA for repeated measures with Bonferroni post-hoc test or Mann-Whitney test, as appropriate
  5. ‡ p < 0.05 versus t1; Friedman test with Dunn’s test for multiple comparisons, as appropriate